I recently was given a couple very nice Stronglight steel cottered cranks. I was waiting for a project to use them on when I got my hands on a Gitane Interclub that was donated to the Bike Exchange. I thought it would be a nice upgrade to the Somewhat less well finished crank on the bike. After stripping the bike and regreasing the spindle bearings I went to install the crank arms only to find that they didn't fit, being a mil to large in diameter. Pulling out about a dozen old spindles I had in the shop I tried all of them on the Stronglight crank and they were all a hair too large for the Stronglight cranks. I then went in to the Bike Exchange and pulled out all the cottered spindles we had. I found at least 3 distinct diameters among them. Luckily I got 2 that fit the stronglight cranks. Most were larger and one was even smaller than the stronglight.

Does anyone have any further info on this topic. I also found 2 different spindle lengths in the pile with different offsets right and left. I had assumed that since all cottered cranks were for double chainrings and 120 mm dropouts they would all have the same profile.

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there are two main diameters for cottered spindles:

British & Metric

Brit is 5/8" / 15.88mm nominal / 15.75mm actual

Metric 16mm nominal, 15.9mm actual


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Don’t forget about the many single chainring cottered cranks found on 3 and 5 speed roadster style bikes. Lots of those produced from many different countries of origin. Spindle length could vary on these single chainring models also.

I would guess that near the arm size of the crank there is an "A". That means it is for an English (Anglais) spindle. Example below:




I came across the same issue.

Here's what Sutherland's (4th ed.) has to say about cottered bottom bracket axles:

The "A" is for acier (steel) and 49 "D" indicates "duralumin" (alloy)

I did not know that, despite having a Sutherland's right here. I presume that, over the years, I just got lucky and never ran into a mismatch.

That's a lot more detail than my 1974 edition has!

Not correct in this application. The "A" is for Anglais or English spindle. The "A" is by the arm size, not the model number. The model 45, which is the pic I shared, did not appear in a Duraluminum model. So there is/was no need to indicate a steel or Duraluminum model. Your statement is correct when applied to the 49 model, but the crank in question is cottered and the 45 is the only Stronglight model that used 50.4 BCD and is cottered

My experience is limited, but I think all of the 3 pin cottered Stronglight cranks I have messed with are from 70's Raleigh Super Courses. I have no idea wether a Raleigh spindle is compatable with French cups, but that would be the first thing I would try

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mfr catalogue page of 1958 -



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I've never seen a Stronglight cotter crank or spindle that wasn't "anglais" size, so why would they need to mark it as such? It's the Italian stuff that uses the larger diameter "metric" spindles in my experience.

Using your logic, why would they need to mark a Stronglight 45 as steel (A) when that is the only way it was produced? What you say may hold true for other Stronglight cottered cranks. . As ISO, French, and Italian spindles are nominal 16mm, it would make sense to mark the oddball English diameter. The pic I shared is of the first Stronglight 45 I bought for a French project bike. It did not fit. Did some due diligence and learned about the different spindle sizes. Also learned the meaning of the "A". Sold the first set and now have a set with no "A" that work.

And remember, gotta love the French.

Thanks for all thr info on cottered cranks. I work on more of these than I want to. I am tempted to buy a cotter press if they were affordable . luckily the Bike Exchange has one I can use.

Here are a couple pictures of the bike I wanted to put the Stronglight crank on, an early 70's ? Gitane Inter club . Gotta love that purple paint. I was going to put yellow bar tape on it but the cheap tape we had broke when I was wrapping the bars. I am not sure what the proper way is to wrap bars without hoods.

So here are the pictures. For its age the bike was in very good condition. The decals were almost completely intact. I only changed the front and rear derailleurs for something a bit more durable. I also swapped out the sew up rims for clinchers and gave it bar end shifters. We have a ton of them at the shop and I think they are easier and safer to use than down tube units. no looking down every time you shift.

Another variant to be aware of is cranks for touring or utility bikes had more room between the crank and the chainring, to allow fitting a chainguard aka pants guard. Racing-oriented cranks have less room there to keep the "tread" ("Q-factor") as narrow as they can. So for the same chain-line, the race crank uses a shorter spindle.

I think some vintage track cranks don't even have room for a derailer cage between the chainring and the crank, so they can't really be adapted to a 2x drivetrain. Narrow tread was a selling point to racers, especially pre-WWII.